1. Field of the Invention
The present invention relates to disk drives. More particularly, the present invention relates to disk drives having a head disk assembly enclosure including insert molded components and methods for manufacturing such disk drives.
2. Description of the Prior Art and Related Information
A typical hard disk drive includes a head disk assembly (“HDA”) and a printed circuit board assembly (“PCBA”). The HDA includes at least one magnetic disk (“disk”), a spindle motor for rotating the disk, and a head stack assembly (“HSA”) that includes a head with at least one transducer for reading and writing data. The HSA is controllably positioned by a servo system in order to read or write information from or to particular tracks on the disk. The typical HSA has three primary portions: (1) an actuator assembly that moves in response to the servo control system; (2) a head gimbal assembly (“HGA”) that extends from the actuator assembly and biases the head toward the disk; and (3) a flex cable assembly that provides an electrical interconnect with minimal constraint on movement.
A typical HGA includes a load beam, a gimbal attached to an end of the load beam, and a head attached to the gimbal. The load beam has a spring function that provides a “gram load” biasing force and a hinge function that permits the head to follow the surface contour of the spinning disk. The load beam has an actuator end that connects to the actuator arm and a gimbal end that connects to the gimbal that carries the head and transmits the gram load biasing force to the head to “load” the head against the disk. A rapidly spinning disk develops a laminar airflow above its surface that lifts the head away from the disk in opposition to the gram load biasing force. The head is said to be “flying” over the disk when in this state.
Within the HDA, the spindle motor rotates the disk or disks, which are the media to and from which the data signals are transmitted via the head on the gimbal attached to the load beam. The transfer rate of the data signals is a function of rotational speed of the spindle motor; the faster the rotational speed, the higher the transfer rate. A spindle motor is essentially an electro-magnetic device in which the electro-magnetic poles of a stator are switched on and off in a given sequence to drive a hub or a shaft in rotation, the hub including a permanent magnetic ring.
FIG. 1 shows the principal components of a traditional magnetic disk drive 100 constructed in accordance with the prior art. With reference to FIG. 1, the disk drive 100 is an Integrated Drive Electronics (IDE) drive comprising a HDA 144 and a PCBA 114. The HDA 144 includes a base 116 and a separate, discrete cover 117 attached to the base 116 that collectively house a disk stack 123 that includes a plurality of magnetic disks (of which only a first disk 111 and a second disk 112 are shown in FIG. 1), a spindle motor 113 attached to the base 116 for rotating the disk stack 123, an HSA 120, and a pivot bearing cartridge 184 (such as a stainless steel pivot bearing cartridge, for example) that rotatably supports the HSA 120 on the base 116. The base 116 is typically attached to the separate cover 117 by means of screws or other discrete fasteners. The spindle motor 113 rotates the disk stack 123 at a constant angular velocity about a spindle motor rotation axis 175. The HSA 120 comprises a swing-type or rotary actuator assembly 130, at least one HGA 110, and a flex circuit cable assembly 180. The rotary actuator assembly 130 includes a body portion 140, at least one actuator arm 160 cantilevered from the body portion 140, and a coil portion 150 cantilevered from the body portion 140 in an opposite direction from the actuator arm 160. The actuator arm 160 supports the HGA 110 with a head. The flex cable assembly 180 includes a flex circuit cable and a flex clamp 159. The HSA 120 is pivotally secured to the base 116 via the pivot-bearing cartridge 184 so that the head at the distal end of the HGA 110 may be moved over a recording surface of the disks 111, 112. The pivot-bearing cartridge 184 enables the HSA 120 to pivot about a pivot axis, shown in FIG. 1 at reference numeral 182. The storage capacity of the HDA 111 may be increased by including additional disks in the disk stack 123 and by an HSA 120 having a vertical stack of HGAs 110 supported by multiple actuator arms 160.
Current trends appear to favor ever-smaller disk drives for use in a wide variety of devices, such as digital cameras, digital video cameras and other audio-visual (AV) equipment and portable computing devices, for example. As an example of the ever increasing reduction in size of disk drives, a new 1″ form factor disk drive was recently introduced by IBM with the intention of fitting it into a port designed for solid state flash memory.
In traditional larger disk drives, all components are discrete and require many steps to assemble. In these traditional larger disk drives separate components are inserted and secured to a base in a conventional manufacturing process. Usually, one or two components are added and secured (most commonly with screws or press-fits) at each assembly station then moved down stream to subsequent assembly operations. However, with the evolution toward smaller and lower cost disk drives, these traditional methods of manufacture may not be optimal with respect to creating smaller and less expensive disk drives.
As disk drives are designed to fit very small form factors, manufacturing and packaging these small disk drives becomes a very big challenge. How to fit in the disks, heads, voice coil motor (VCM) plates, motors, actuators, etc., in a stiff enclosure to achieve the requisite mechanical requirements is increasingly difficult. Further, in addition to the mechanical requirements, electrical components also take up a significant portion of the available volume in a small form factor drive. Because of the ever more stringent size constraints imposed upon disk drive manufacturers and the highly cost competitive nature of the disk drive industry, disk drive manufacturers are desperately trying to find ways to minimize both disk drive size, as well as costs. Simplifying the manufacturing process is one avenue that disk drive manufacturers are exploring, with the rationale that fewer manufacturing steps lead to smaller and less costly drives. Toward that end, attention has turned to the disk drive enclosure as one possible candidate for size and cost reductions.